The objective of this collaborative case-control study is to examine the role of diet and metabolism in the etiology of epithelial ovarian cancer. The proposed five-year investigation will include 273 Asian-American (Japanese, Chinese, Filipino) and 273 Caucasian women with histologically- confirmed, epithelial ovarian cancer identified in Hawaii and Los Angeles. One control will be frequency-matched to each case on age, ethnicity, and geographic area. Common methodology and a standardized personal interview will be used in the two study areas. The interview will be conducted in the subjects' homes and will include the following content areas: a diet history evaluating total dietary intake of calories and nutrients, a reproductive and gynecologic history, use of oral contraceptives and other hormones, medical history, cancer history in first-degree relatives, physical activity, and height and weight. Various body measurements will be taken to estimate the amount of body fat and its distribution. A lactose hydrogen breath test will be used to demonstrate lactose malabsorption or intolerance. A blood specimen will be obtained to measure the activity of enzymes involved with the metabolism of galactose. The study design and sample size will allow us to examine the association of ovarian cancer with 1) the dietary intake of calories, lipids, lactose, antioxidants, and fruits and vegetables; 2) lactase persistence and levels of galactose-1-phosphate uridyl transferase activity, galactokinase and UDPgalactose-4-epimerase; 3) obesity, body fat distribution, and physical activity; and 4) familial aggregation of cancer. This study utilizes the substantial differences in lifestyle and incidence of ovarian cancer between Asian-American and Caucasian women to elucidate the etiology of a devastating cancer. It offers a unique opportunity to investigate the association of diet, and other environmental and genetic factors with the risk of ovarian cancer. The establishment of a relation between dietary practices or enzyme deficiencies and the risk of epithelial ovarian cancer would have implications for cancer screening activities and the targeting of high risk groups for educational programs and dietary intervention.